1. Field of the Invention
The present invention relates to an esterase gene and a use of the same.
2. Description of the Prior Art
An (S)-N-substituted cyclic imino acid represented by the general formula (2): 
wherein R2 is an aralkyl group having 7 to 19 carbon atoms; an alkylcarbonyl group having 2 to 5 carbon atoms, an arylcarbonyl group having 7 to 13 carbon atoms; an alkyloxycarbonyl group having 2 to 9 carbon atoms; an aralkyloxycarbonyl group having 8 to 10 carbon atoms; an alkenyloxycarbonyl group having 3 to 9 carbon atoms; an aryloxycarbonyl group having 7 to 13 carbon atoms; an alkyl group having 1 to 8 carbon atoms; an alkenyl group having 2 to 8 carbon atoms; an aryl group having 6 to 12 carbon atoms; or an arylsulfonyl group having 6 to 12 carbon atoms, and one or more hydrogen atoms bound to an aromatic ring of said aralkyl, arylcarbonyl, aralkyloxycarbonyl, aryloxycarbonyl, aryl or arylsulfonyl group may optionally be substituted with at least one selected from an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, a halogen atom and a nitro group, and one or more hydrogen atoms in said alkylcarbonyl, alkyloxycarbonyl or alkyl group may optionally be substituted with at least one selected from an alkoxy group having 1 to 8 carbon atoms, a halogen atom and a nitro group;
and n is 1 or 2.
Compounds of formula (2) (hereinafter referred to sometimes as the (S)-cyclic imino acid (2)) are useful intermediates for a pharmaceutical.
Among such (S)-cyclic imino acid (2) compounds is an N-substituted-azetidine-2-carboxylic acid represented by the general formula (3): 
wherein R2 is a hydrogen atom or a protective group, and *is an asymmetric carbon atom. N-substituted-azetidine-2-carboxylic acid is produced biologically using a biocatalyst, which is an enzyme derived from a microorganism such as Candida antarctica, Penicillium camembertii, Rhizopus chinensis, Rhizopus japonicus, Mucor javanicus, Mucor miehei, Bacillus subtilis, Candida rugosa, Candida cylindracea, Pseudomonas cepacia, Bacillus licheniformis, Bacillus sp., and Aspergillus niger, as described in JP-A-11-46784 (1999). The optical purity (% ee) of the enzyme, an intrinsic property determined based on the molecular structure of the enzyme, is also described in JP-A-11-46784 (1999).
An objective of the present invention is to provide a novel gene encoding a protein having an excellent catalyst ability for producing (S)-cyclic imino acid (2) and to provide a novel method for producing (S)-cyclic imino acid (2) by an asymmetric hydrolization of the N-substituted cyclic imino acid ester represented by the general formula (1): 
wherein R1 is an alkyl group having 1 to 8 carbon atoms, an aralkyl group having 7 to 19 carbon atoms, an alkenyl group having 2 to 5 carbon atoms or an aryl group having 6 to 12 carbon atoms, and one or more hydrogen atoms in said alkyl group may optionally be substituted with at least one selected from an alkoxyl group having 1 to 8 carbon atoms, a halogen atom and a nitro group and one or more hydrogen atoms bound to an aromatic ring in said aralkyl or aryl group may optionally be substituted with at least one selected from an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, a halogen atom or a nitro group;
and R2 and n are defined as described above (hereinafter referred to sometimes as the cyclic imino acid ester (1)) in a manner of gene engineering technology utilizing the novel gene provided.
Accordingly, Applicants have found a novel gene encoding a protein having an excellent catalyst ability for producing (S)-cyclic imino acid (2), thereby arriving at the present invention.
Scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
Throughout this specification and the claims which follow, unless the context requires otherwise, the word xe2x80x9ccomprisexe2x80x9d, and variations such as xe2x80x9ccomprisesxe2x80x9d and xe2x80x9ccomprisingxe2x80x9d, will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integer or step.